Parental Care Flashcards
Threats to offspring (7)
Predation Hypoxia Temperature Food shortages Parasites Pathogens Desiccation
Why is parental care useful to parents?
Improves their reproductive fitness and so increases gene propogation
Physiological basis of parental care in birds?
Seems genetic, denoting neural circuitry: nest building, feeding mechanisms very specific
Forms of care? (7)
Provisioning of gametes Oviposition site selection Nest building/burrowing Egg/offspring attendance Egg/offspring brooding Food provisioning Care after nutritional independence
Provisioning of gametes?
Providing energy/nutrients to the egg
May cover with defensive secretions
Egg/offspring attendance?
Post-fertilisation care, it is the most common form
Egg/offspring brooding?
Reduced cost of care compared to attendance as it allows food location and predator avoidance
Food provisioning? (4 forms)
Indirect - offspring find food themselves, directed by parents
Direct via regurgitation
Direct via provision of actual food
Specialised food source from parent e.g. milk, matriphagy
Care after nutritional independence?
Bewick’s swan - help offspring compete for food
Often in longer-lived vertebrates
Costs of parental care? (4)
Increased predation risk
Physiological costs e.g. body mass loss
Energy expensive
Food loss
Divisions of care?
Maternal
Paternal
Bi-parental
Division of care in birds?
90% bi
8% maternal
2% paternal
Why do birds show parental care?
Altricial young
Few sex-specific adaptations i.e. both build nests, both incubate and feed
Evidence for ancestral paternal care in birds?
Fossil record - therapod dinosaurs have similar clutch volume:adult body mass ratio to modern paternal birds
Primitive birds e.g. ratitites show paternal care
Why might paternal care evolve in birds?
Females incur greater energetic costs producing large eggs and so males must provide care
=cost of care and of large eggs
Egg protection = females attracted to defended territories
Forms of care in mammals? (3)
Always maternal, sometimes bi
Monotremes = egg incubation in pouches where milk seeps in
Marsupials = pouch
Placentals = most common
Evolution of care in mammals?
Maternal = ancestral
Bi-parental has evolved 9 times, lost 3
Care in fish?
Only about 30% of species, some bi, more paternal than maternal
Fish care mechanisms? (4)
Hiding eggs
Nest building
Egg and fry protection
Fanning for nest oxygenation
How many times has male-only care evolved in fish?
22 times, in lineages with external fertilisation
What groups show care?
Mammals Birds Fish Reptiles Amphibians Arthropods
Why is it often female care? (2)
Parental investment hypothesis
Parental certainty
Parental investment hypothesis?
Sex that invests less in gametes will invest less after mating
Why do (externally fertilising) fish show parental care?
Desertion opportunity
Association
